They mix beaten egg white with earth of which they make the first layer of the crown of a bell in pieces. They also make bells and all other said pieces which the said egg white. This makes it come clean and sets and stabilizes the material. For the core of a small piece, egg white is also good.
Rosette in order to make it come clean, wants the mold to be a little hot and lead which is mixed with the red copper is therefore chiefly for small pieces.